Infrared detectors may include infrared (“IR”) sensitive components located on a suspended diaphragm. The diaphragm may be relatively thin to reduce the thermal conductance of the diaphragm and thereby improve the sensitivity of the detector. The diaphragms of existing infrared detector may include a layer of silicon nitride. However, diaphragms of such construction may be fragile which may reduce manufacturing yields and limit the ability to further process the detector after formation of the diaphragm. Furthermore, due to its high thermal conductivity the silicon nitride layer may provide significant thermal loss.
In order to minimize breakage the fabrication process may be arranged such that the diaphragm is formed as the final step. However, this procedure limits the flexibility of the manufacturing process and of course limits the ability to add additional components after the formation of the diaphragm. Further, even when the diaphragm is formed as the last step of the manufacturing process, the diaphragm may sufficiently fragile to be prone to breakage during packaging or handling of the detector.
Accordingly, there is a need for a infrared detector having a diaphragm which has a relatively low thermal conductance, is relatively robust, and can withstand a variety of chemical etchants.